Numerous valves are known for controlling or metering the flow of fluids, defined herein as the flow of gases and liquids. These valves are suitable for use with fluids pressurized to relatively low pressures which are either flowing with large rates of flow; or are not flowing at all, as when stored in a pressure vessel.
Existing valves are disclosed in: U.S. Pat. No. 3,956,604, dated May 11, 1976, to Larper et al; U.S. Pat. No. 4,077,569, dated Mar. 7, 1978, to Deines; U.S. Pat. No. 4,199,004, dated Apr. 22, 1980, to Wada et al; U.S. Pat. No. 3,322,155 dated May 30, 1967, to Julow; and U.S. Pat. No. 4,108,327, dated Aug. 22, 1978, to Shonerd et al.
Such exemplary valves are unable to meter high pressure fluids, defined herein as pressures of about 20,000 to 60,000 psi, at a slow rate, such as the ability to pressurize a 1 liter vessel with helium at about 25 psi per minute.
Traditional valves typically employ a tapered stem and seat. An exemplary valve is activated by a pneumatic piston through a lever arm. Disadvantages of such a valve system are: the tapered seats cannot repeatedly achieve shut-off at high pressures of greater than about 20,000 psi and are also subject to galling; and the sliding motion within the valve contributes to hysteresis, making it unsuitable for automatic control.
It would be an advancement in the art of valve technology to provide a valve system which could controllably meter high pressures of greater than about 20,000 psi, particularly at a slow rate. It would be a further advancement to achieve the preceding without the occurrence of tangential sliding motion between stem and seat. Another advancement would be to provide a valve system where the indication of flow rate is related to the force applied to the valve rather than as a result of displacement.